Dell networking - N3048P latency problems

Hi Dell community,

I would like to get an opinion on a latency problem im facing between a security camera and its remote controller. Here is the most basic setup where my problem appears: I have 2 dell N3048P switches (switch A & switch B) linked via redundant fibers through Switch C which is a Dell S4820 (limited availability at the time). At that point, everything works well together until i notice that the camera, connected on switch A, responds to the commands of its remote controller (connected on the same switch) with 2 to 5 seconds of latency. There is at max 1Gbps of bandwith used by IP video on the uplinks so far from being saturated and the TCP commands do not even need to pass over the uplinks. At least they don't (when i mirrored the port, while noticing that latency problem, not a single packet of this traffic was going trough the uplinks). RSTP is configured correctly and one of the 2 links is up at a time.

Here's the twist, when i disconnect the uplinks, the latency problem disappear... but not a single packet of the traffic was passing through it, but still it changes its behavior. I checked the switching capacity which is still far from its top.

Could a long queue of IP video being prioritized on the switching plan cause that much trouble ?

Would QoS be a solution or did someone encountered that kind of behavior and might help me

Thanks.

Regards,